Grinding machine



Oct. LJUNGGREN 2,429,830

GRINDING MACHINE Filed Aug. 22, 1942 8 Sheets-Sheet l T. H. LJUNGGRENGRINDING MACHINE Filed Aug; 22. 1942 8 Sheets-Sheet 5- Oct. 28, 1947.'r. H. LJUNGGREN GRINDING MACHINE Filed Au 22, 1942 a Sheets-Sheets Oct.28, 1947. T. H. LJUNGGREN GRINDING MACHINE Filed Aug. 22, 1942 8Sheets-Sheet 6 Q0 5 E f i M w EN sq 5 g E 3 s S 3 \m E 0a; 28, 1947. "r.H. LJU GGREN 4 9,

I GRINDING MACHINE Filed Au 22, 1942 e she ts-sheet a Patented Oct. 28,.1947

UNITED STATES OFFICE GRINDING momma Thor H. Ljunggre'n, Charlestown, N.H.. assignor to Bryant chucking Grinder Company, spring- 1 field, Vt.,a'corporation of yermont r V Application August 22, 1942, SerialNo;.455,-737 31 Claims. (or 51-50) This invention relates to metalworking machines, and in its more specific aspects, to grindingmachines.

One object of the invention is to provide improved controls for thecycle of operation.

A further object is to provide mechanism for moving the work andgrinding wheel operated by fluid pressure, preferably hydraulic,together with electrical control of the fluid pressure mechanism.

Still another objectis to provide for an automatic cycle of operationsincluding rough and finish grinding with truing of the grinding wheelbetween the rough and finish grindings and with limit stopsindependently adjustable to determine the limits of wheel feed for bothrough and-finish grinding.

A further object is to provide for a feed and retractive motion ofpredetermined extent and superposed thereon an additional small feedincrement to compensate for wheel wear and truing.

For a complete understanding of this inven-- tion, reference may be hadto the accompanying drawings in which Figures 1 and 2 are fragmentaryfront and top plan views of an internal grinding machine embodying theinvention. I

Figure la is a detail sectional View on line la-la of Figure 1.

Figure 3 is a detail sectionalview on line 3 3 of Figure 1, i

Figures 4 and 5 are detail sectional views on lines 4-4 and 55,respectively, of Figure 3.

Figures 6 and 7 are detail sectional views on lines E--5 and 1-1,respectively, of Figure 5.

Figure 8 is a fragmentary left end elevation of parts shown in Figures 1and 5.

Figure 9 is a detail sectional view on line 9-9 of Figure 8.

Figure 10 is a detail sectional View on line [0-40 of Figure 9.

Figure 11 is a diagrammatic view showing the control and actuatingmechanism in position for rough grinding and with the wheel traversingto the left.

Figure 11a is a fragmentary top plan showing a control member.

Figure 12 is a view similar to Figure 11, but showing the parts in dressposition between rough and finish grinding.

Figure 13 is a view similar to Figures 11 and 12, but showing the partsin final grinding position traversing to the left.

Figure 14 is a diagram showing the parts in final fast traverseposition.

Figure 15' is a view similar to portions of Figures 11' to 13 but withthe parts shown in position for traverse of the: wheel to the right.

Y Figure 16 is an elevation of an electrically actuated switch showndiagrammatically in Figures 11 to 14, inclusive.

Referring first to Figures 1, 2 and 3, the machine as shown is aninternal grinding machine. This machineis provided with a bed 1 havingmounted at the left hand end thereon a work holder carriage 2. This workholder carriage carries thereon 'a.--head 3 which is angularlyadjustable along curved ways 4.- It supports a rotary'workspindlecarryingat its right hand end asuitable work holding chuck 5, andat its left end pulleysfi and 1. Either selected of these pulleys may beconnected as by the V-belts 8 to aicorresponding pulley 9 or 10 on theshaft of a motor indicated generally at H, this motor providing meansfor rotating the work'carried by the ehuck-5 and indicated generally atl2. This work holder -2 is mounted for sliding motion from front toback, thus providing for a feed motion-between the wheel and the work.The feed mechanism will be further described.

To the lighter the work holder 2 is mounted a wheel carriage I5rotatably supporting a spindle l6 carrying a wheel shaft I! at the endof which is carried the grinding wheel l8. This wheel carriage isfixedto a tubular member 20 (see Figure 3) which is rockably and axiallymovable on arcuate bearing members, one of which is shown at Zi inFigure 3. The member 23 is formed with acentral partition 2| as shownbest in Figure 11, and forms a pair of axially alined cylindersreceiving through their outer ends a pair of. tubes 22 through whichfluid may be passed into or discharged from the respective cylindersthrough the pipes 23 and 24, thus to produce axial. reciprocation of themember 23, and with it, a corresponding motion of the wheel carriage I5.This motion of the wheel carriage produces the desired traverse of thework by the grinding wheel during the grinding operation, as wellunderstood 'in'the art.

Feed mechanism As before noted the feed between the work and the wheelis produced by motion of the work transverse to the traverse direction.Referring to Figure 8, the work carriage 2 has a bracket 25 secured to adepending front apron portion 26 as by screws 21. This bracket hasjournaled therein a feed shaft 28. TIhe rearor inner end of this feedshaft is formed. as a feedscrew 30 which is 3 threaded through a nut 3|mounted for rotation in a sleeve 32 of a bearing 33 carried by the baseI of the machine. It will be evident that feed may be produced either byrotating the shaft 28 or by rotating the nut 3 I.

Rotation of the shaft 28 may be produced by rotation of a hand wheel 29having a hub portion 290 secured to the shaft 28, as by means of a nut29I engaging a threaded extremity of the shaft 28. Shaft 28 may also berotated by the rotation of a gear ring 34 secured to the hub portion 290as by screws 35. This gear ring 34 acts as aworm wheel and may haveengaged therewith a worm 37 keyed to a shaft 38 to the outer end ofwhich is keyed a suitable hand knob 39 by which it may be turned asshown in Figure 4. This shaft 38 is journaled eccentrically in a bushing40 having a hub II to which is secured a handle 42. By turning thisbushing 40 to bring its handle 42 between the full line position and thedotted line position of Figure 4, the shaft 38 is lifted bodily so as tolift the worm 31 out of contact with the gear ring 34. In this positionthe shaft 28 may be turned freely by rotation of the hand wheel 29. Inthe full line position shown in Figure 4, the engagement of the worm 31with the gear 34 look the shaft 28 against turning by rotation of thehand wheel 29 but permits a very slow rotation to be imparted thereto byrotation of the hand knob 39. This mechanism provides an operatoractuatable mechanism for determining the initial feed position as whensetting up the machine.

The feed may then be effected by power in accordance with thepredetermined cycle of the machine. This power feed is produced byrotation of the nut 3| for which purpose there is secured thereto, as byscrews 45, a ring gear 48. This ring gear projects through an opening 41in the top wall of the bed I and meshes with a gear 48 havinga hubportion 49 journaled on a bush n 58 carried by a stud shaft secured to abracket 52 as shown in Figures 3 and 5. This bracket 52 is secured to apartition member 53 of the base I as by screws 54. The hub 49 isprovided with an integral worm wheel portion 56, which as shown best inFigure 5, meshes with the threads on an externally threaded quill 58.This quill forms the piston rod of a power feed cylinder 80, the quillhaving an enlarged diameter portion 6I fittin within the cylinder 69 anda somewhat smaller diameter extension 62, which is guided through thecylinder head 63. The cylinder 85 and its head 63 are fixed to the feedbracket 52 as by screws 64. The quill 58 is mounted for both axial androtary motion within the cylinder 80 and when moved axially its threadsact as a rack in engagement with the teeth of the worm gear 56. Thisaxial motion of the quill produces the normal feed motion of the workrelative to the wheel, while rotary motion of the quill produces a slowadditional feed motion, which is for the purpose of compensating forwheel wear and truing.

Rotation of the quill 58 may be produced by rotation of a splined shaft65, the splined portion of which extends into an enlarged bore 66 of thequill; This shaft 65 is journaled in a bearing 68 and just rearwardly ofthis hearing it is provided with the outer or cup member (see Figures 5and 6) of a one direction roll clutch device. The inner member II ofthis clutch device is carried by a shaft I2 and between these elementsand seated in inclined recesses in the inner clutch element II are theclutch balls I3. Rotation of the shaft 12 in one direction, therefore,serves to rotate the splined'shaft 65 and through it the 4 quill 58,thus to produce as low rotation of the worm wheel 58 while rotation ofthe shaft I2 in the opposite direction is ineffective to transmitturning motion to the quill.

The shaft 65 may also be locked against rotation, except when it isdesired to turn it. This may be produced by forming the outer peripheryof the cup element '10 with serrations into which may be projected theedge of a locking bolt I5 (see Figures 5 and 6). This locking bolt mayhave a head 78 riding in a fluid pressure cylinder 71 and may benormally pressed into locking engagement with the cup element I0 as by aspring 18. A screw 79 extending through the cylinder wall and engagingin a slot 80 in the head 16 prevents the locking bolt 75 from beingturned out of position to properly register with the serrations of theelement 10. This locking bolt may be retracted by fluid pressureadmitted above the head '18 as through a pipe 8|. Retraction of thelockin bolt 15 opens a port leading to a pipe 82 from which fluidpressure may be 1ed to a mechanism for rotating the shaft 85.

Fluid pressure mechanism for rotating the shaft 85 is shown best inFigure 7. The rear end of the shaft 12 has fixed thereto a pinion 85with which meshes rack teeth on a cylindrical rack bar 88. This rack barforms the plunger of a hydraulic cylinder 81 and is provided with a head88 at its inner end which may abut against an adjusting stop screw 89threaded through the head 90 of a hydraulic cylinder. The plunger isnormally held in this position as by means of a coil spring 93 seated ina socket 9| in the outer end of the plunger engaging over a centeringpin 92 carried by the fixed frame member 53. The pipe 82 permits fluidunder pressure to be introduced into the pressure cylinder 81, thisacting to force the plunger 85 outwardly to rotate the pinion 85 in onedirection, while when the fluid under pressure is permitted to dischargethrough the pipe 82, the spring 98 forces the plunger back and turns thegear 85 in the opposite direction. A check valve 85 (Figures 11 to 14)prevents the fiuid under pressure from reaching the cylinder 87 from thepipe 8| so that the latch bolt has to be first released, opening thepipe 82. The direction 6i motion produced by the fluid under pressure issuch as to rotate the shaft I2 in the direction to turn the splinedshaft 85 and thereby rotate the quill 58.

As before noted, the axial motion of the quill 58 produces the normalfeed motion of the work carriage, and this feed is produced by motion ofthe quill to the left from the position shown in Figure 5. Its limit ofmotion is determined by either of a pair of switch actuating stops I08and It! which are mounted for sliding motion through a plunger I82. Thisplunger is supported adjacent to opposite ends in cylindrical guidemembers I83 and I84. The guide member I83 is provided with a key way I85fOr the reception of a key I85 carried by the plunger I62 and by whichthis plunger I82 is prevented from turning. The plunger I82 is normallyurged toward the position shown in Figures 5, 9, l2 and 13 as by aspring I01 seated in a socket I98 in one end of the plunger and reactingagainst a head plate I09 bridging across the cylindrical bore of theguide member I83 and fixed as by the screws H0. The bore of the guidemember I 84 forms a hydraulic cylinder closed off at its outer end by acover plate II 5 secured in position as by the screws H6, and throughthis cover plate extends a hydraulic pipe II 8 through which fluid under14 the stop IDI rather than the stop I is in lallnement with the plug420.

The stops I00 and .IllI, as shown, are identical in construction.Referring to .Ffigure 9, each stop comprises a screw I having -a headi216 which facilitates turning .it .for adjustment, .this screw havingthreaded engagement in .a sleeve I21 which is slidably keyed in a boreI28 of the plunger I02. At its inner end this sleeve I21 has an enlargedhead I38 with an enlarged diameter flange I3I. Between this flange and.a

counterbored portion .IBZ of the bore of the plunger I23 is positioned acoil spring [33 which acts to holdthe stop projected toward the plug I20 as far as is permitted by a collar -I 35 threaded onto a. portion ofthe sleeve I2] and secured in adjusted position thereon as by .a, setscrew 135. By turning the screw I25 the amount by which it projectsbeyond the head I33) maybe adjusted,

and it may be fixed .in such adjusted position as by a lock nut M0threaded thereon and bearing against the rear extremity of the sleeveI21. It will thus be seen that the stops are individually adjustableaxially and as shown one of these, the stop MI, is adjusted furtherinwardly than the stop I00. This stop l.0.I limitsthe extent of feed fora rough grinding operation and this limit, of

course, should .be somewhat short of the .full

depth of cut. The stop I 00 is set for .the final work dimension as the.result of a finishing out and is therefore retracted by the amountrequired for the finishing cut over the position .of the stop IOI.

The axial motion permitted these stops is made use of to actuate a pairof controlling electric switches .shown at I and I46 (see Figures 8,.9and'lO) and these are actuated simultaneous- 1y by the rocking of alever plate 14] iournaled between two cone centers I48 and I45 carriedby a. forked supporting plate I50 securedto a bracket I5I (see Figure10) as by the screws I52. one end of the plate I4], as at I55, projectssuficieinz- 'ly toward the stops so that it may be engaged by either ofthe collars I35 which happens to be opposite thereto, depending on theaxial position of the plunger I02, so that when the stop engaged by theplug I20 of the quill is pushed outwardly thereby, the lever I4! isrocked from the position shown in Figure 10 until it contacts anddepresses the two push button switches I45 and 146. This lever plate I4!is normally held away from the push button switches as by a leaf springI and in contact with a. stop pin I51. The functions of the switches I45and I46 will be later explained.

While the .feed is taking place there is also efiected a traverse of thewheel relative to the work. This is done automatically and during thenormal grinding operation the traverse is produced through an amplitudeof definite length. .As will later appear, after the rough grinding hasbeen effected, the machine is conditioned automatically for an extendedtraverse of the wheel in one direction which brings it away from thework, and during this extended traverse the wheel is trued. The machineis then automatically conditioned to return to the grindin cycle toeffect finish grinding within the normal grind- 6 ing traverse limitsand the stop plunger is moved to present the .finish grinding .stop intooperative position, The feed is resumed and when the desired finish sizeis ground, the grinding cycle stops with the wheel at .afurther-extended traverse .limit .away from the work, whereupon theground work maybe removed and an unground piece substituted therefor.The cycle of grinding for the new .piece may then be initiated by theoperator.

' Traverse mechanism Asshown the means for producing traverse of thework carriage is hydraulic, the control being fihroughaplurality ofvalves, some of which are controlled by electrical circuits as willlater appear. Movable with the tubular member 20, and thus with thewheel carriage, is a support 200 having a .phira'lity of longitudinalgrooves therein along which may he adjustabl-y fixed stops 2!, 202 and203. The stop MI is longer than the stops 202 and 203 and .determinesthe limit of stroke of the wheel carriage inwardly. The stop 202 .is theshortest of the three and determines the outer limit of traversingmotion during the normal .grinding operation only, The stop 203 isintermediate in length between the stops 20! and 202 and determines theoutward limit f extended traverse during which the wheel is dressed.Another limit of outward motion at which the finished work is removedand new work to be ground inserted .is determined by the maximum travelof the wheel slide which is reached when the partition 2| contacts withthe end of the member 22.

The determination of which of these stops is effective at any time isefiected by the axial position of a .control member 204 which may bemoved axially by hydraulic means and is also permitted a rocking motion.The rocking motion acts to reverse the direction of traverse at thedesired traverse limits. Eccentric to this member 204 is a post 205projecting therefrom which may be struck by the stops 202 or 203 as thewheel carriage traverses, depending on the axial position of'the member204, to rock the member 204 in one direction, while contact of the stop20I with the post 205 or on a cutaway edge of the collar portion 200 ofthe member 204 (see Figure 11a) acts to rock the member 204 in theopposite direction. This general arrangement per so with the three stopsand a rockable and axially movable control member is not per so myinvention, but the construction of the member 204 and associated partsand its hydraulic control does form a portion thereof. This member 204is rockably carried by a yoke 208, but is connected for axial motiontherewith. This may be produced by providing the yoke member 208 with ashaft extension 209 having a peripheral groove 2I0 therein, this shaftextension bein rotatable within a socket 2 in the lower end of themember 204. Any suitable means, such as a set screw 2 I2 having itsinner end riding in the peripheral groove 2), may be employed to retainthe yoke and member 204 in assembled relation for simultaneous axialmotion but with capability of relative rotation. The yoke member 208 hasa central plunger portion 2I4 which projects into a casing 2I5 withinwhich is slidable a cup member 2I6 having a shank portion 2II. Thisshank portion projects through the lower end of the casing 2I5 andthrough it extends a port 2 I8 connecting with a pressure supply anddischarge pipe 2 I 9. A similar pipe 220 passes through the wall of theeasing 215 and opens up beneath the cup-shaped portion 2I5 outwardly ofits shank 2H. When fluid pressure is admitted through the passage 2|8,the plunger H4 is lifted to its top position as shown in Figure 11, atwhich time the element 205 is in position to contact the stop 202, whileeither the element 205 or the cut away portion of the flange 206 remainsin all of the axial positions of member 204 in position to be contactedby the stop 20L If the fluid pressure is not admitted through the pipe2l9 and the port 2|8, the plunger 2l4 may descend to the bottom of thecup 2H5, and where this cup 216 is in its lowered position as shown inFigure 11, the member 2| 4 is then in its lowest position as shown inFigure 14. In this position the element 205 is too low to be contactedby either of the stops 202 and 203 and the grinding wheel carriage canthen make its full stroke away from the stop 21 to the work loading andunloading position, When fluid pressure is introduced through the pipe220 beneath the cup member 216, this cup member is lifted to its upperposition shown in Figure 12 and with the member 204 in a, position whichis intermediate to its top and bottom positions and in which it may becontacted by the stop 203, but is too low to be contacted by the stop202. The grinding wheel may then take its extended traverse for truing.

It will be noted that when contact is made on the member 204 with any ofthe stops, it is turned angularly first in one and then in the otherdirection. This turning causes reversal of the direction of traverse ofthe wheel carriage. To this end a portion of the length of the member204 on its back face is provided with gear teeth which mesh with teethof a rack bar 225. This rack bar is a part of or forms an extension to apilot valve 226, and rocking of the member 284 from one to the other ofits Positions changes the axial position of the pilot valve 226 betweenthe positions shown in Figures 11 and 15.

Referring first to Figure 11, a liquid suitable for a hydraulic system,such as oil, is pumped from the supply reservoir 230 by the pump 23!into a pipe 232. A pressure relief valve at 233 connected to the pipe232 and leading back to the tank 230' limits the pressure of the liquidin the pressure pipe 232. This pipe 232 leads to a valve casing 234having within it a reciprocable reversing valve 235. In the positionshown in Figure 11, the reversing valve is at the right hand end of itscylinder, opening communication from the pressure pipe 232, around theneck 236 of the reversing valve, through the pipe 23'! to the casing 238of the pilot valve, around the neck 239 of this pilot valve and into anaxial passage 240 therein, and out around the neck 241 of this pilotvalve through the pipes 242, 2420 t the left hand end of the reversingvalve, thus retainin the reversing valve in the position shown. Thefluid under pressure also passes around the neck portion 236 of thereversing valve through the pipe 23 and the member 22 into the righthand end of the cylinder 20, thus to move this cylinder and the wheelcarriage to the left. At the same time liquid is escaping from the lefthand end of the cylinder 20 through the pipe 24, around the neck 245 ofthe reversing valve, pipe 245, to the pilot valve, around the neck 24!of this pilot valve and through the pipe 243 to the valve casing 249within which is axially slidable the valve 250 fixed to one arm of theyoke 208, the discharge passage around a neck 25! of this valve, throughthe pipes 252 and 2520, through the throttle valves 253 and 2530, andthe pipe 254 to the discharge pipe 255,

through the pipes 260 and 26!, around the neck 262 of the pilot valve,through the central passage 263, around the neck 264 of the pilot valve,and. out through the discharge line 255. After the pipe 260 has beenclosed by the reversing valve as shown in Figure 11, discharge continuesto take.

place through the pipe 26l at the end of the valve at a reduced rate ofspeed until the valve is in its extreme right hand position shown. Thisarrangement of the two end pipes 250, 26| and 242 and 2420 leading fromthe reversing valve, one of which is shut oif before the other one,provides for the slowing down of the travel of the reversing valveadjacent to the ends of its stroke and this with the tapered end of thevalve head 2360, for a dwell in the motion of the wheel slide.

When the member 204 is turned by impingement of the member 201 thereon,the pivot Valve 226 then takes the position of Figure 15. In thisposition pressure from the pressure pipe 232 passin to the reversingvalve casing 235 with the reversing valve in the position of Figure 11,passes around the neck 236 of this reversin valve, through the pipe 231to the pilot valve, around the neck 239 of this pilot valve, as shown inFigure 15, through the axial passage 265 to the pipes 201 and 260, whilethe pipes 242 and 2420 at the left hand end of the reversing valve areconnected around the neck 210 of the pilot valve through the axialpassage 2', and the neck 212 of the pilot valve to the discharge pipe255. Thus the reversin valve is pushed to its left hand position shownin Figure 15 where the pressure pipe 232 is connected around the neck245 of this valve to the pipe 24 leading to the left hand end of thecylinder 20, while the pipe 23 is connected around the neck 23B of thereversing valve and the pipe 231, around the neck 24! of the pilotvalve, and to discharge through the pipe 248, as previously described.The direction of carriage travel is thus reversed. On turning of themember 204 back to its original position so that the pilot valve 226 isin the position shown in Figure 11, and the pilot valve is in theposition shown in Figure 15, the pressure connections to the pilot valveand to the reversing valve through the pilot valve are as previouslydescribed, causing the reversing valve to be moved to the position ofFigure 11, and reversing the pressure and discharge passages withrespect to the ends of the cylinder 20. This action of reversing takesplace regardless of the axial position of the member 204, so long asthere is some means for turning the member 204,

At the end of the cycle of operations where the member 204 is too low tobe contacted by either of the stops 202 or 203, and the carriageproceeds to its extreme outward limit of motion, where it stops forloading and unloading, there is nothing to turn the member 204 to effectreversal, hence the machine stops at this position. When it is desiredto start it again, the operator turns the member 204 by hand as by meansof the handle 215, whereupon the traverse commences, the member 204being lifted first to its uppermost position by mechanism which willlater be described.

Cycle control mechanism Besides carrying the valve 250, the yoke 200ans-sea also carries another valve 280' having a pair of necks 281 and282 and this valve forms part of the mechanism which controls the feedmotion of the work carriage which is operated from a pressure circuitindependent of that which operates the wheel traverse.

The axial position of the member 204 is determined by the pressurecircuit which operates the traverse, through electrically controlledvalves A and B. The wheel feed and retraction is controlled byelectrically actuated valves and I), while the positioning of the roughgrinding and finish grindin stops is controlled. by the electricallyoperated valves E and F. All of these valves A, B, C, D, E, and F are ofthe same construction, each being provided with a singleneck between twoheads, and each controlling connections between a single pipe on oneside and two pipes on the other so as to connect the two pipesalternately to the single pipe, depending upon the valve position. Eachof these valves is normally held in. one axial position, but is adaptedto be moved to the other axial position by energization of an actuatingcoil A, B, C, D, E, and F, respectively, and these are controlled partlyby the switches 145 and 145, three relays 3'00, 301, and 302 and two motor actuated switches 303 and 304. Each of the motor actuated switches303 and 304- is of the type shown in Figure 16, in which energization ofa motor 305 rotates a cam. 306. The rotation of this cam 306, actingupon a follower lever 30'1, first closes contacts at 300 and 309, assoon as this rotation has been permitted by the re lease of a latchmember 3l0 from a notch 3100 in a disk 31'! rotatable with the cam 306,by energization of the solenoid 311. Such energization pulls backwardlyon a hook 312 which engages the lower end of the latch 310 and alsocloses contacts at 313 and 314 which complete the circuit to the motor305 through a lead 315 in parallel with the solenoid 311,,starting-rotation of the motor. The solenoid 31 1 retracts the hook 312until it snaps out of. contact with the latch 3H1 which then rides onthe surface of. the disk 311 rotatable with the cam 306 and holds themotor control contacts 313' and 314 closed until the camhas made acomplete rev olution, whereupon the latch snaps back into the notch3100', opening the contacts 313 and 314, stopping further rotation ofthe motor305, and permitting the hook 312 on de-energization of thesolenoid 301 to be brought back by a spring into catching relation withthe latch 310, the hook yielding to pass beneath the latch 3 and engageits forward face. The action of: each of the switches 303 and 304'istherefore to close a circuit for a short time and then after apredetermined interval to open it again, the opening taking place whenthe cam 306 permits the fol-.- lower portion 301 to break the contactsat 309.

Each of the relays 300', 301 and 302 take either of two positions, eachhavin a pair of spaced solenoids with an armature therebetween, thearmature being attracted to one or the other of the solenoids, dependingupon which one is energized at a particular time, and the position ofthe armature defining. the position of a plurality of pivotally mountedswitch arms. As shown each of these armatures is one arm of a bell cranklever, the other arm of which is con.-

nected to a rod pivotally connectedito the various switch armscontrolled thereby, spaced from their pivots. The relay 300 is providedwith an armature 320 10 which is connected through the rod 321 with theswitch arms" 322;, 3'23, 324 and 325-, and it has the actuatingsolenoids 326 and 321'. The switch 301 is provided with an armature 330which actuates the switch rodl33l] controlling the switch arms 332, 333,as! and 335', and is provided with the actuating solenoids 33B and 331'.The relay 302 is rovided with an armature m which ati .tiiat'es'tne'switch' controlling'rodf 3t! controlling the" positions if theswitch arms 34'? and 343', and it? is provided with the actuatingsolen'o'i'd's 381 andstfi. a In tne'positicn' of the parts shown inFigure 1'1 hiring an intermediate portion of the rough gr nding thevalve coils A" and E are energized, whilethe valve coils B, C", 'D" andF" are not energized. The valve A is then in position foriiuidpres'sure'from the pressure line 232 to reach this valve throughthe pipe 350, to pass around the neck 351 of this valve, and through thepipe Zililintb' the cup member-1 ls ben-eani the plunger 214', thusholding the member 204 in its highest position where it is in positionto bev imp'in'g'ed upon on; opposite ends of its traverse by the stops202 and 201", tfhus't'o produce the relative" snort working traverseorthe wheel carriage; Thi energiza'tion of theyalve coil A produced fromthe power lines 335 mm 3stthrough the lead from the line 3B5,, tnecci11i, lead 358, contact 359", switcnarm azt of relay b, and leadfluid under pressur from a pressure ump 3'65, 7

drawing. from the'supply'tank' 230, through a pressure-pipe-SGB inlwhichthe pressure is limited by the pressure relief valve 305 dischargingback into the supply tank 230, through pipes 361 and 36a to the valve E,around the neck 36!! of this valve; and through'thepipe 310' to thelower end 01? the member 102. before noted; this upper positibn'ofthemember 2M holds" the valve membe: 250 in its-uppermost positionwherein the discharge of fluid from the traversin cylinder for bothdirections of traverse takes place through thctlirottle valves 233- and2530, thereby holding the speed or traverse to the desired low value.Iii-the same position of the member'zlll' and duri'ng grinding,thevalvemember 230' is in its uppermost position in v'vliichfluid underpressure from the pressure pipe 366 reaching the valve 201 passes aroundthe neck 282 of this valve and through the pipe 3'11 to" the right handend of the feed cylinder 60; while the mild under pressure is dischargedirom the left hand end of this cylinder through the pipe 3'12, aroundthe neck 281 of the valve" 280; through the pipe 313', around the neck314 of the valve C, through the pipe 3'15, around the neck 316 of thevalve D, through the pipe 311 and the throttle valve 310 to' thedischarge pipe 319,-whi'cli leads back to the supply tank 230'. Thespeed of'feed is thus governed by thesetting of'tlieth'rottl e'valve3T8.

It is desirable in the retracted relative positions of the wheel andwork, that the wheel be spaced somewhat from the work in order to fullyclear it. In order tosave time it is therefore desirable to feed thewheel and work relatively from the wheel retracted position quickly tobring the wheel up close to the workand thereafter toproduce feed. atthe slower normal speed proper for cutting. Means to provide thisinitial relatively 11 quick feed comprise the hydraulic valve C withassociated parts and its controlling switch 304. In the position of therelay 300 shown in Figure 11, the switch arm 324 is closed, closing acircuit from the line 356 through lead 360, switch arm 324, lead 3040,the solenoid 3H and then the motor of the switch 304 and lead 3042 toline 355. This acts immediately to close and hold closed but for only alimited time the switch arm 304i, which closes a circuit from line 356through leads M4, 3043, switch arm 304I, lead 3044, solenoid C and lead3045 to line 355. This moves the valve to a position where dischargefrom pipe 313 passes around the neck of valve C, through the pipe 3140to the discharge pipe 319, cutting out the restricted discharge throughpipe 315 past the valve D and through the throttle valve 381. As soon asthe motor of switch 304 allows the switch arm 3042 to open, the valvesolenoid C becomes de-energized, and the valve C returns to its upwardposition as shown, the initial rapid feed having already been completed,whereupon the unrestricted discharge is cut ofi and the dischargethrottled by the valve 318. Further feed during the rough grinding thenproceeds slowly after the rapid initial feed which brings the work andwheel close together. The switch 304 with its motor drive is thus atiming device controlling the time of the rapid initial idle feedbetween the work and wheel which brings them close to each other beforethe slow working feed is thrown in. The slow feed is thus in action whenthe wheel and work contact and during the entire time of grinding. Theslow grinding feed continues, the wheel traversing the work and beinggradually fed into the work until the feed sleeve 58 through its plugI20 contacts the stop IOI which it pushes outwardly against the leverI41 (see Figure until it closes both of the switches I45 and I46.

The closing of the switch I45 closes a circuit from the line 355,through leads 380, 38I, switch I45, lead 382, solenoid 321 of the relay300, lead 383, switch arm 323 of relay 300, lead 360 back to the line356. This moves the armature 320 over to the solenoid 321, and in doingthis it breaks the connection between the switch arm 323 and the lead383, thus immediately de-energizing the solenoid 321, the relay 300 thenbeing in the position shown in Figure 12. The closing of the switch I46acts to close a circuit from the line 356 through the leads 385 and 386,switch I46, lead 381, switch arm 343, lead 388, solenoid 331 of theswitch 30I, lead 389, switch arm 332 and lead 390, back to the line 355.This immediately throws the armature 330 over toward the solenoid 321,which immediately breaks the contact between the switch arm 332 and thelead 389, thus opening the circuit through the solenoid 331, but leavingthe switch 30I in the condition shown in Figure 12. It will thus be seenthat the relays 300 and 30I have been thrown to their opposite positionsfrom the showing of Figure 11 to the showing of Figure 12, but for thepresent the relay 302 remains in the position of Figure 11.

With the switches 300 and 30I in the position of Figure 12, the solenoidA has been de-energized through the breaking of the contact between theswitch arm 325 of relay 300 and the lead 359 so that the valve A takesits other position. This connects the pipe 2I9 around the valve neck 35Iof the valve A, through the pipe 39I t0 the disc arge P pe 255, so thatthe plunger 2I4 descends to the bottom of the cup member 216. However,the valve coil 13 is new ener ized by closing of the switch arm 325 tothe lead 421, which completes the circuit from the line 356, lead 360,switch arm 325, lead 42I, coil B, lead 420, switch arm 335, lead 390' toline 355 so that pressure from the pressure pipe 350 passes around theneck 393 of valve B through the pipe 220, be:- neath the cup member 2I6, thus raising this cup member, together with the plunger 2| 4. Thereversal of the positions of the relays 300 and 30I thus acts to lowerthe member 204 one step to its truing position as shown in Figure 12.This lowering of the member 204 lowers the valv 280 from the positionshown in Figure 11 to that shown in Figure 12, reversing the connectionsfrom the fluid pressure line 366, so that pressure now flows through theline 312 to the left hand end of the feed cylinder 60 and connects thepipe 31I from the right hand end of the feed cylinder to around neck 282of the valve 280 through the ipe 3130 to the discharge pipe 313. Thisdischarge is unrestricted so that the feed quill is returned quickly toits starting position. In this position of the member 204, also, thevalve 250 has moved from the position in Figure 11 to the position shownin Figure 12, so that the discharge of fluid from the pilot valve casingthrough the pipe 248 no longer takes place through both of the throttlevalves 253 and-2530, the pipe 2520 having been blanked by the valve 250,but takes place through the single throttle valve 253 so that the speedof traverse is reduced, at which time the stop 202 is no longereffective to reverse the direction of traverse so that the wheel slideis given an extended traverse until the stop 203 is effective, andduring this extended traverse the wheel is automatically trued. Thepressure from this pipe 220 also flows through a pipe 394 to a cylinder395 of a wheel truing device 396 (shown best in Figure 1a) passing tothe left of a piston 391 whose piston rod is connected to one arm 392 ofa bell crank lever, the other arm of which carries the truing diamond. Aspring 398 engaging the back face of the piston 391 holds the bell cranklever tilted with the truing device at the inoperative position exceptwhen pressure is applied to the cylinder 395 through the pipe 220. Thisinoperative position is shown in full lines in Figure 1a and Figures-11, 13 and 14. This truing device is positioned as shown in Fi ures 1and 2 beyond the end of the work, where when the truing device is inoperative position, it will be engaged by the grinding wheel during itsextended traverse, thus to true the wheel.

The throwing of the relay 30I from the position shown in Figure 11 tothat shown in Figure 12 closed the switch arm 334 to the lead 408 whichestablished a circuit from the line 355, lead 390, switch arm 334, lead408 and 409, to the motor of the switch 303 and lead 4I0 to the line356. This, as before noted, closed for a short period the switch arm 4I5which established a circuit from the line 355 through the leads 380 and412, solenoid F, lead 4I3, switch arm 5, lead M4 to the line 356.Energization of the solenoid F pulled the valve F downwardly for a shortperiod of time and in this downward position, fluid from the pressureline 366 and pipes 361 and 368 passing the neck of this valve flowedinto the pipe BI which acted to pull the latch 15 into unlockingposition and thereafter to force the plunger 88 inwardly from theposition shown in Figure '1 to impart rotation to the gear the extent ofwhich was determined by the setting of the stop 89 shown in Figure 7,thus turning the splined shaft 15 tracted position, while the pipe 248leading from the pilot valve casing is connected directly to dischargethrough the pipes 565 and 355. As there is no throttle valve in thisdischarge path, the final outward traverse is at a rapid rate.

The finished ground work may then be removed from the machine and newwork placed in position therein. The machine may then be started byturning the member 204 by hand, as by operation of the handle 205, tostart the inward traverse. As the dog 400 passes beneath the switch 40!on this inward traverse itcloses this switch, re-establishing a circuitbetween the leads 402 and 385. This completes the circuit from the line356 through lead 385, switch 4M, leads 402 and 4551, switch arm 322,left hand solenoid 326 of the relay 300, lead 45!, to the line 355. Italso establishes a connection from the lead 402, through the switch arm342 of relay 362, the left hand solenoid 344 of this relay, lead 4',switch arm 333 of relay 30!, and lead 350 to line 355. This acts toreturn the relays 300 and 302 to the positions shown in Figure 11, thusautomatically conditioning the machine for the rough grinding operationas previously described between the.

stop limits 2!)! and 262, lifting the member 254 to its grind position,giving a fast and then a slower machine feed, and lifting the stopcarrying member I02 to position the rough grinding stop l! intoalinement with the plug I20 and the machine repeats its cycle,

From the foregoing description of an embodiment of this invention, itshould be evident to those skilled in the art that various changes andmodifications might be made without departing from the spirit or scopeof this invention.

I claim:

1. A carriage moving means including a rotary shaft, connections fromsaid shaft to said carriage causing rotation of said shaft to move saidcarriage, a gear fixed to said shaft, an externally threaded quillengaging the teeth of said gear and mounted for axial and rotationalmotion, the threads of said quill acting as a rack with respect to theteeth of said gear on axial motion of said quill and as a worm onrotation of said quill, a rotary shaft splined to said quill, means formoving said quill axially to impart a relatively rapid rotation to saidrotary shaft, and means for rotating said splined shaft to impart arelatively slow rotation to said first mentioned rotary shaft.

2. A carriage moving means including a rotary shaft, connections fromsaid shaft to said carriage causing rotation of said shaft to move saidcarriage, a gear fixed to said shaft, an externally threaded quillengaging the teeth of said gear, said quill having a piston portion, afluid pressure cylinder within which said piston and quill may moveaxially and rotate, fluid pressure means communicating with saidcylinder for moving said quill axially, said quill then acting as a rackwith respect to said gear, a shaft splined to said quill, and means forrotating said splined shaft, said quill acting as a worm with respect tosaid gear on rotation of said quill.

3. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage in a direction tofeed a grinding wheel on said carriage relative to work on said holder,said moving means comprising a one direction driving clutch, an osciloutmotion of said plunger, spring means for re- 16 turning said plunger onrelease of fluid pressure thereon, and means effective to apply andrelease fluid pressure on said plunger.

4. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage in a direction tofeed a grinding wheel on said carriage relative to work on said holder,said moving means comprising a one direction driving clutch, anoscillatory shaft for driving said clutch, a fluid pres sure actuatedplunger connected to said shaft to rock said shaft in oppositedirections by in and out motion of said plunger, spring means forreturning said plunger on release of fluid pressure thereon, a latchengageable with said moving means and biased to hold said moving meansstationary, fluid pressure means for first retracting said latch andthen acting on said plunger, and means for controlling said fluidpressure means.

5. In combination with a movable carriage havng a grinding Wheel mountedthereon, a wheel truing device, means for moving said carriage to feedthe grinding wheel relative to work and to said wheel truing device,said carriage moving means comprisinga rotary shaft, connections fromsaid shaft to said carriage causing rotation of said shaft to move saidcarriage, a gear fixed to said shaft, an externally threaded quillengaging the teeth of said gear, andmounted for axial and rotationalmotion, the threads of said quill acting as a rack with respect to theteeth of said gear on axial motion of said quill to effect normal feedof said wheel relative to the work and to said device, and acting as aworm on rotation of said quill to effect a further slight feed of saiddevice relative to the wheel to compensate for wheel wear and truing,means for moving said quill axially, and means for rotating said quill.

6. A grinding machine having a work holder, a, grinding wheel carriage,means for relatively moving said holder and carriage in a direction tofeed and retract a wheel on said carriage relative to work on saidholder, a pair of means selectively actuated by said feeding means forreturning said feeding means to starting position after a predeterminedextent of feed, one of said pair of means being set to permit a'greaterfeed motion than the other pair ofmeans, and means acting automaticallyon return. of said feeding means to starting position by the action ofthe means of said pair set for the less feed for restoring said feedingmeans to feeding actuation.

'1. A grindin machine having a work holder,

a grinding wheel carriage, means for relatively moving said holder andcarriage to effect traverse of said wheel along work carried by saidholder, means for relatively moving said holder and wheel transverse tothe line of traverse to produce relative feed between the work andwheel, a pair of movable stops one or the other of which may be madeoperative to limit the extent of feed, means for automatically movingsaid stops to position one of said stops into operative position tolimit the feed and consequent depth of cut for a rough grindingoperation and thereafter to position the other of said stops intooperativeposition to limit the feed and consequent depth of cut duringfinish grinding, and means actuated by each stop when the feed isstopped thereby, to actuate said trans-'- verse moving means in reverseto separate the work and wheel to a predetermined feed startingposition.

8. A grinding machine having a work carriage. a grinding wheel carriage,means for moving one of said carriages to produce a relative traverseefiecting reversal of traversedirections said member being movable toany of three positions to cooperate selectively with certain of saidelements to thereby select the amplitude of traverse at one-end -tonormal grinding, extended truing, or to and from a loading and unloadingposition, a truing device movable; to and from operative position totrue the wheel in said extended traverse, and means controlled by theposition of said member to control the speed of traverse to a slowgrinding speed while said member is in grinding position, to a slowerspeed when said member is in truing position and to operatively positionsaid truing device so that the wheel is trued by said device duringextended traverse, and to a fast speed when said member is in loadingand unloading position.

9. A grinding machine having a work carriage, a grinding wheel carriage,means for moving one of said carriages to produces. relative traversebetween said 'carriagcs, elements movable with said movable carriagedefining traverse limits, 2.

member with which said elements cooperate for,

effecting reversal of traverse directions, said member being movable toany of three positions to cooperate selectively with certain of saidelements to thereby select the amplitude of traverse at one end tonormal grinding, extended truing, or to and from a loading and unloadingposition, a truing device movable to and from operative position to truethe wheel in said extended traverse,

means controlled by the position of said member to control the speed oftraverse to a slow grinding speed while said memberis in grindingposition, to a slower speed when said member is in truing position andto operatively position saidtr'ui'ng device so that the wheel istrued-by said device during extended traverse, and to a fast speed whensaid member is in loading and unloading position, and mechanism.automatically moving said memher in predetermined sequence from one toanother of said positions to define a cycle of operations of themachine.

10. A grinding machine having a work carriage, a grinding wheelcarriage, means for moving one of said carriages to. produce a relativetraverse between said carria es, elements movable with said movablecarriage defining traverse limits, a member with which said elementscooperate for effecting reversal of traverse directions, said memberbeing movable to any of three positions to cooperate selectively withcertain of said elements to thereby select the amplitude of traverse atone end to normal grinding, extended truing, or to and from a loadingand unloading position, a truing device movable to and from operativeposition to true the Wheel in said extended traverse, means controlledby the position of said member to control the speed of traverse to aslow grinding speed while said member is in grinding position, to aslower speed when said member is in truing position and to operativelyposition said truing device so that the wheel is trued by said deviceduring extended traverse, and to a fast speed when said member is inloading and unloading position, means for effecting relative feed andretraction between said carriages, and mechanism partly responsive tothe relative feeding relation between said carriages for moving saidmember in predetermined sequence from one to another of said positionsto define a cycle of operations of the machine.

11. A grinding machine having a work carriage, a grinding wheelcarriage, means for moving one of said carriages to produce a relativetraverse between said carriages, elements movable with said movablecarriage defining traverse limits, a. member with which said elementscooperate for eflccting reversal of traverse directions, said memberbeing movable to any of three positions to cooperate selectively withcertain of said-elements to thereby select the amplitude of traverse atone end .to normal grinding, extended truing, or to and from a loadingand unloading position, altruing device movable to and from operativeposition to true the wheel in said extended traverse, means controlledby the position of said member to control the speed of traverse to aslow grinding speed while said member is in grinding position, to aslower speed when said member is in truing position and to operativelposition said truing device so that the wheel is trued by said deviceduring extended traverse, and to a fast speed when said member is inloading and unloadlng position, means for effecting relative feed andretraction between said carriages, and mechanism partly responsive tothe relative feeding relation between said carriages and partlyresponsive to the traverse relation between said carriages for movingsaid member in predetermined sequence from one toanother of saidpositlons to define a cycle of operations of the ma chine.

12. A grinding machine having a work carriage, a grinding wheelcarriage, means for moving one of said carriages to produce a relativetraverse between said carriages, elements movable with said movablecarriage defining traverse limits, a member with which said elementscooperate for efiecting reversal of traverse directions, said memberbeing movable to any of three positions to cooperate selectively withcertain of said elements to thereby select the amplitude of traverse atone end to normal grinding, extended truing, or to and from a loadingand unloading position, a truing device movable to and from operativeposition to true the wheel in said extended traverse, means controlledby the position of said member to'control the speed of traverse to aslow grinding speed while said member is in grinding position, to aslower speed when said member is in truing position and to operativelposition said truing device so that the wheel is trued by said deviceduring extended traverse, and to a fast speed when said member is inloading and unloading position, means for effecting relative feed andretraction between said carriages, means controlled by said feedingmeans when said carriages reach a predetermined relative feed positionto condition said feeding and retracting means to retract said carriagesrelatively from said position, and mechanism actuated in part by themotion of said one carriage at a. predetermined point in its traversepath and in part by said controlling means when so actuated, for movingsaid member in predetermined sequence from one to another of saidpositions to define an automatic cycle of operations of the machine.

13. A machine of the class described, comprising a tool carriage, a workholding carriage, means for moving one of said carriages to produce arelative traverse motion between said carriages, stops carried by saidone carriage and projecting by different amounts therefrom, a memberrockably mounted to be turned by impingement thereon of said stopsadjacent to traverse limits of said one carriage, said member beingmounted for adjustment toward and from said stops, a non-rockableaxially movable member secured to said rockable member for simultaneous,axial motion therewith, said non-rockable member having a plungerportion, connections from said rockable member to said carriage movingmeans causing the rock ing of said rockable member by impingement ofsaid stops thereon to reverse the direction of traverse, a. fluidpressure cylinder within which said plunger portion extends, and meansfor controlling a supply of fluid pressure to said cylinder to therebydetermine the axial position of said rockable member and thus determinethe limits of traverse motion.

14. A machine of the class described, comprising a tool carriage, a workholding carriage, means for moving one of said carriages to produce arelative traverse motion between said carriages, stops carried by saidone carriage and projecting by different amounts therefrom, a memberrockably mounted to be turned by impingement thereon of said stopsadjacent to traverse limits of said movable carriage, said member beingmounted for adjustment toward and from said stops, a non-rockableaxially movable member secured to said rockable member for simultaneousaxial motion therewith, said non-rockable member having a plungerportion and a control portion, connections from said rockable member tosaid carriage moving means causing the rocking of said rockable memberby impingement of said stops thereon to reverse the direction oftraverse, a fluid pressure cylinder within which said plunger portionextends, means for controlling a supply of fluid pressure to saidcylinder to thereby determine the axial position of said rockable memberand thus determine the limits of traverse motion, and means controlledby the position of said control portion for determining the rate ofmotion of said one carriage.

15. A machine of the class described, comprising a tool carriage, a workholding carriage, means for moving one of said carriages to produce arelative traverse motion between said carriages, a tool carried by saidtool carriage, means for moving one of said carriages transverse to thedirection of traverse to feed said tool and work holding carriagerelatively, stops carried by said traversing carriage and projectindifferent amounts therefrom, a member rockably mounted to be turned byimpingement thereon of said stops adjacent to traverse limits of saidtraversing carriage, said member being mounted for adjustment toward andfrom said stops, a nonrockable axially movable member secured to saidrockable member for simultaneous axial motion therewith, saidnon-rockable member having a plunger portion and a control portion,connections from said rockable member to said carriage moving meanscausing the rocking of said rockable member by impingement of said stopsthereon to reverse the direction of traverse, a fluid pressure cylinderwithin which said plunger portion extends, means for controlling asupply of fluid pressure to said cylinder to thereby determine the axialposition of said rockable member and thereby determining the limits oftraverse motion, and means controlled by the position of said controlportion to determine the limit of said feed motion.

16. A machine of the class described, comprising a tool carriage, a workholding carriage, means for moving one of said carriages to produce arelative traverse motion between said carriages, stops carried by onecarriage and project- 20 ing by dififerent amounts therefrom, a memberrockably mounted to be turned by impingement thereon of said stopsadjacent to traverse limits of said movable carriage, said member beingmounted for adjustment toward and from said stops, a non-rockableaxially movable member secured to said rockable member for simultaneousaxial motion therewith, said non-rockable member having a plungerportion and a valve portion, connections from said rockable member tosaid carriage moving means causing the rocking of said rockable memberby impingement of said stops thereon to reverse the direction oftraverse, a fluid pressure cylinder within which said plunger portionextends, fluid pressure means for controlling a supply of fluid pressureto said cylinder to thereby determine the axial position of saidrockable member and thus determine the limits of traverse motion, andfluid pressure means controlled by the position of said valve portionfor determining the rate of motion of said one carriage.

1'7. A machine of the class described, comprising a tool carriage, awork holding carriage, means for moving one of said carriages to pro?duce a relative traverse motion between said carriages, a tool carriedby said tool carriage, work carried by said work carriage, means formoving one of said carriages transverse to the direction of traverse tofeed said tool and work relatively, stops carried by said traversingcarriage and projecting different amounts therefrom, a member rockablymounted to be turned by impingement thereon or said stops adjacent totraverse limits of said traversing carriage, said member being mountedfor adjustment toward and from said stops, a non-rockable axiallymovable member secured to said rockable member for simultaneous axialmotion therewith, said non-rockable member having plunger portion and avalve portion, connections from said rockable member to said carriagemoving means causing the rocking of said rockable member by impingementof said stops thereon to reverse the direction of traverse, a fluidpressure cylinder within which said plunger portion extends, means forcontrolling a, supply of fluid pressure to said cylinder to therebydetermine the axial position of said rockable member and therebydetermining the limits of traverse motion, and fluid pressure meanscontrolled by the position of said valve portion to determine the limitof said feed motion.

18. A machine of the class described, comprising a tool carriage, a workcarriage, means for effecting relative traverse between said carriages,mean producing relative feed between said carriages transverse to thedirection of traverse, said traversing means including elements stoppingthe traverse at points defining the traverse limits, a movable memberselectively cooperating with certain of said elements to determine bythe position of said member which of said certain ele ment shall beeffective, means actuated by said feed producing means at the feed limitfor moving said movable member to a, difierent position, and meanscontrolled by said member in accordance with its position determiningthe speed of traverse,

19. A machine of the class described, comprising a grinding wheelcarriage, a work carriage, means for traversing one of said carriageswith respect to the other carriage, spaced stop elements carried by saidtraversing carriage and extending to different distances therefrom, thelongest of said stops defining one limit of traverse motion. a shorterstop defining the other limit of an extended traverse, and a stop ofintermediate length defining the other limit of a working traverse, arockable and axially movable member extending toward the path of motionof said stops and having three definite axial positions in all of whichit is in the path of motion of said longest stop to be rocked in onedirection by impingement of said longest stop thereon, in the inner ofwhich axial positions said member is in position to be impinged upon bysaid shortest stop to be rocked thereby into another angular position,and in the intermediate of which positions it is not contacted by saidshortest stop but is contacted and rocked to said other angular positionby the stop of intermediate length, and in the outermost position saidmember is contacted by neither said shortest stop nor said stop ofintermediate length, a wheel truing device positioned to act on a wheelcarried by said wheel carriage during said extended traverse, operativeconnections between said member and traversing means causing rocking ofsaid member by said stops to reverse the direction of traverse, andmechanism effective to position said member in each of said axialpositions in a predetermined cycle.

20. A- machine of the class described, comprising a tool carriage, awork carriage, means producing a relativ feed between said carriagesfrom a retracted position when a tool on said tool carriage is out ofcontact with work on said work carriage, means normally limiting therate of such feed, a normally open switch, a rotary cam engaging saidswitch and having a surface portlon positioned to close said switch, a,latch normally holding said cam stationary in angular positionpermitting said switch to be open, a motor for turning said cam, anelectrically operated device acting when energized to momentarily tripsaid latch allowing said cam to be turned and to close a circuit to saidmotor, said cam having a surface portion engaging and holding open saidlatch during a predetermined extent of rotation of said cam during whichsaid switch is closed and then allowed to open, means for energizingsaid device at the start of such feed from the retracted position, andmeans responsive to the closing of said normally open switch andoperative only so long as said switch remains closed for renderinginoperative said rate limiting means to increase the rate of feed tobring the work and tool close together after which said rate limitingmeans is effective to slow the rate of feed.

21. A machine of the class described, comprising a grinding wheelcarriage, a wheel truing mechanism, means for presenting said mechanismin wheel truing position and then retracting said mechanism, a normallyopen switch, a rotary cam engaging said switch and having a surfaceportion positioned to close said switch, a latch normally holding saidcam stationary in angular position permitting said switch to be open, amotor for turning said cam, an electrically operated device acting whenenergized to momentarily trip said latch allowing said cam to be turnedand to close a circuit to said motor, said cam having a surface portionengaging and holding open said latch during a. predetermined extent ofrotation of said cam during which said switch is closed and then allowedto open, means energizing said device when said mechanism presenting 22nismand carriage relatively to compensate for wheel wear and trains.

22. A grinding machine having a. work holder. a grinding wheel carriage.hydraulically actuated means for relatively moving said holder and carrge in a direction to feed a wheel on said carriage relative to work onsaid holder, means actuated by said feeding means after a predeterminedamount of feed for returning said feed means to starting position, meansacting automatically thereafter to restore said feeding means to feedingactuation, and means actuated by said feeding means automatically aftera predetermined amount of feed larger than the amount for said firstfeeding motion to return said feeding means to starting Position.

23. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage to effect traverseof said wheel along work carried by said holder, means for relativelymoving said holder and wheel transverse to the line of traverse andduring such traverse to produce relative feed between the work andwheel, a pair of stops one or the other of which may be made operativeto limit the extent of feed, and means for automatically moving bothstops to position one of said stops into operative position and theother out of operative position to limit the feed and consequent depthof cut for a rough grinding operation and thereafter to position theother of said stops into operative position and said one stop out ofoperative position to limit the feed and consequent depth of cut duringfinish grinding.

24. A machine or the class described, comprising a tool carriage, a workcarriage, means for moving one of said carriages relative to the othercarriage to eflect relative traverse between said carriages, means formoving one of said carriages relative to the other carriage transverseto the direction of traverse to effect a relative feed and retractionbetween said carriages, said traverse moving means including a reversingmember movable to control the direction of traverse, elements carrled bythe movable carria e for actuating said reversing member to reverse thetraverse direction, said member being movable into and out ofcooperative relation to certain of said traverse reversing actuatingelements to selectively limit the length of traverse in ac cordance withthe position of said member relative to said elements, feed limitingelements selectively positioned to control said feed moving means tolimit the feed between said carriages to different amounts, and meansactuated by the feed moving means through the limiting element selectedat any one time to determine the position of said member and thus thelimit of traverse of the next succeeding traverse motion.

25. A machine of the class described, comprising a tool carriage, a workcarriage, means for moving one of said carriages relative to the othercarriage to efiect relative traverse between said carriages, means formoving one of said carriages relative to the other carriage transverseto the direction of traverse to effect a relative feed and retractionbetween said carriages, said traverse moving means including a reversingmember movable to control the direction of traverse. elements carried bythe movable carriage for actuating said reversing memher to reverse thetraverse direction, said member being movable into and out ofcooperative relation to certain of said traverse reversing actuatingelements to selectively limit the length 23 of traverse in accordancewith the position of said member relative to said elements, feedlimiting elements movable to position one or another in cooperativerelation to said feed moving means to control said feed moving means tolimit the feed between said carriages to difierent amounts dependingupon which element is in cooperating position, means actuated by thefeed moving means through the limiting element in cooperative relationto said feed moving means at any one time to determine the position ofsaid member and thus the limit of traverse of the next succeedingtraverse motion, and means controlled by said member in accordance withits position for determining the speed of traverse.

26. A machine of the class described having a tool carriage, a workcarriage, means for moving one of said carriages relative to the othercarriage to efiect relative traverse between said carriages, said meansincluding a member operable to reverse the direction of traverse andmovable from one to another of a plurality of operative positions,traverse stops carried by that carriage which is movable for traverseeach stop cooperating with said member in certain of the operativepositions of said member to selectively determine the length oftraverse, means for moving one of said carriages to eiiect relative feedand retraction between said carriages transverse to the line oftraverse, a feed stop carrier, a plurality of feed stops set fordifferent feed limits carried by said carrier, means for moving saidcarrier to present any of said feed stops selectively into operativeposition, means for moving said member from one to another of itsoperative positions, and mechanism controlled partly by said carrier andpartly by said carriages in accordance with their relative positionsactuating said member moving means, said carrier moving means, and bothof said carriage moving means in a predetermined cycle.

27. A machine of the class described having a tool carriage, a workcarriage, means for moving one of said carriages relative to the othercarriage to effect relative traverse between said carriages, said meansincluding a member operable to reverse the direction of traverse andmovable from. one to another of a plurality of operative positions,traverse stops carried by that carriage which is movable for traverseeach stop cooperating with said member in certain of the operativepositions of said member to selectively determine the length oftraverse. means for moving one of said carriages to effect relative feedand retraction between said carriages transverse to the line oftraverse, a feed stop carrier, a plurality of feed stops set fordifferent feed limits carried by said carrier, fluid pressure means formoving said carrier to present any of said feed stops selectively intooperative position, means for moving said member from one to another ofits operative positions, and electrical mechanism controlled partly bysaid carrier and partly by said carriages in accordance with theirrelative positions actuating said member moving means, said carriermoving means, and both of said carriage moving means in a predeterminedcycle.

28. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage to effect traverseof said wheel along work carried by said holder, means for relativelymoving said holder and wheel transverse to the line of traverse andduring such traverse to produce relative feed between the work andwheel, a movable member, a pair of stops carried by said member one orthe other of which may be made operative by movement of said member tolimit the extent of feed and to return said holder and wheel to startingfeed relation, and means for automatically moving said movable member toposition one of said stops into operative position to limit the feed andconsequent depth of cut for a rough grinding operation and the otherstop out of operative position and thereafter moving said movable memberto position said one stop out of operative position and the other ofsaid stops into operative position to limit thefeed and consequent depthof cut during finish grinding.

29. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage to effect traverseof said wheel along work carried by said holder, means for relativelymoving said holder and wheel transverse to the line of traverse toproduce relative feed between the work and wheel, a. pair of movablestops one or the other of which may be made operative to limit theextent of feed, and means for automatically moving said stopssimultaneously to position one said stops into operative position tolimit the feed and consequent depth of cut for a rough grindingoperation and while the other stop is moved out of operative positionand thereafter to position the other of said stops into operativeposition to limit the feed and consequent depth of cut during finishgrinding and while said one stop is moved out of operative position.

30. A grinding machine having a work holder, a grinding wheel carriage,means for relatively moving said holder and carriage to effect traverseof said wheel along work carried by said holder, means for relativelymoving said holder and wheel transverse to the line of traverse andduring such traverse to produce relative feed between the work andwheel, a pair of stops both movable together to present one or the otheroperative to limit the extent of feed while the other is out ofoperative position, means for automatically moving said stops toposition one of said stops into, operative position and the other out ofoperative position to limit the feed and consequent depth of cut for arough grinding operation and thereafter to move said stops to positionthe other of said stops into operative position and said one stop out ofoperative position to limit the feed and consequent depth of cut duringfinish grinding, means for automatically truing the wheel between therough and finish grindings. and supplemental means for automaticallyactuating said feed means an additional amount independent of saidstops, to compensate for wheel wear and truing preparatoiy to truing thewheel.

31. A machine of the class described comprising a tool carriage, a worksupporting carriage, means for effecting relative traverse between saidcarriages, means for producing a relative feed between said carriagestransverse to the direction of traverse, said traversing means includingelements defining different traverse limits, a movable memberselectively cooperating with certain of said traverse elements todetermine by the position of said member which of said certain elementsshall be effective, said feed means including elements definingdifl'erent feed limits, means actuated by said feed producing means atany of said feed limits for moving said movable member to a differentposition to

